Another neighbour, whose house backs onto the property, said she knew the couple.

Mary Pearson, 70, said: “We always talked. I’ve known them seven years. She was a very nice woman, she used to go to the shops every day, even at the age she was, she was ninety-odd.

“I mostly saw him now and again. They were a very nice couple really.”

She described the incident: “I saw the smoke coming out of the back door. There was no windows, no back door open and smoke coming out, but I didn’t hear a fire alarm going off.

“By the time I’ve got my coat on to go round there, someone had gone into the house through the front.

“I think it was the grand daughter who had gone round because she was dropping her children off at school.

“It was a shock, especially for the neighbour next door because she loved her.

“It’s upsetting because she was a very nice neighbour.”

A joint investigation has been launched by the Police and the Fire Services and a post-mortem examination will take place to try to establish the exact cause of death, say police.

Richard Edney, spokesman for Lancashire Fire and Rescue said: "We were called to a house fire at 8.45am this morning. Four firefighters wearing breathing apparatus used hose-reels and ventilation units to enter the property and extinguish the fire.